US site Defense News reports that Honeywell, makers of the F-35's On-Board Oxygen Generation Systems (OBOGS), will be "designing upgraded firmware" to be rolled out to all F-35s.

The OBOGS works via a molecular sieve material called Zeolite. A more detailed explanation can be found here.

The Ministry of Defence confirmed that Britain's F-35s will receive the software upgrade. Blighty currently flies F-35Bs and the oxygen system fitted to F-35As and the B model is identical. The UK has also repeatedly refused to rule out a future order of F-35As, fuelling rumours that the British fleet may be a mixed one.

Hypoxia is a particularly dangerous affliction for pilots. Defined as a lack of oxygen in body tissues, its symptoms range from an increased pulse and breathing rate to drowsiness, dizziness and temporary intellectual impairment. By its very nature, the latter makes it hard for the pilot to recognise and correct.

Virtually all aircraft with pressurised cockpits – from F-35s to airliners – maintain cabin pressure at an equivalent altitude of around about 8,000ft. ®